Concept:Each column follows the Pythagorean triplet pattern: (a)2+(b)2=(c)2.Explanation:First column: (3)2+(4)2=9+16=25=(5)2.So the bottom number is the hypotenuse.Second column: (12)2+(5)2=144+25=169=(13)2.Thus the same rule applies to the third column.Third column: (24)2+(7)2=576+49=625.Since 625=(25)2, the missing number is 25.Answer:25